The embodiments disclosed herein generally relate to document scanning and, more particularly, to a document scanner, an associated method of operating a document scanner, and an associated program storage device wherein the scan mode and, particularly, the light intensity level to scan rate setting, of the document scanner is automatically adjusted, as necessary, to fall within legal requirements and/or recommendations established to prevent vision damage and/or discomfort and still allow for high-resolution scanning.
Generally, a document scanner converts images and/or text on a hardcopy of a document into electronic form. The document scanning process involves placing the document on a top surface of a transparent platen (i.e., a transparent flat plate). A scan carriage is then moved passed the document along the bottom surface of the platen. The scan carriage includes a light source that illuminates the document and, particularly, the images and/or text thereon. The carriage also includes an image sensor, which incorporates photosensitive devices (e.g., photodiodes or other photosensitive devices) that measure the intensity of light reflected from given areas of the document. The sensor data is then translated from analog to digital, thereby defining the picture elements (i.e., pixels) of the document being scanned. Combined these pixels represent the document in electronic form.
Technology advancements in this area have been driven by customer requirements for high-speed, high-resolution, document scanning. Increasing the scan rate of a document scanner (i.e., the speed at which the scanner carriage moves past the document) typically results in a corresponding decrease in the sensing time available to the photosensitive devices and, thereby a corresponding decrease in the resulting image resolution. Additionally, the drive for smaller optics and smaller sensors leads to less efficient light collection and smaller photosites which are less sensitive and, thereby a corresponding decrease in the resulting image resolution. To compensate for decreases in image resolution due to increases in scan speed and/or decreases in smaller optics and sensors, the intensity level of the light that illuminates the document can be increases. As a result, good signal to noise figures and, thereby acceptable images can be achieved in less time using smaller optics and sensors.
Unfortunately, the light intensity levels being used in the newer technology high-speed, high-resolution, document scanners can, depending upon the exposure time, fall outside legal requirements and/or recommendations established to prevent vision damage and/or discomfort. While this, for the most part, is not an issue when the platen cover of the document scanner is closed (e.g., when a document handling system automatically feeds single sheets onto the platen for scanning or when a user places a single sheet on the platen for scanning and closes the cover) as the light is shielded from the user, exposure to high intensity light can become an issue when the platen cover is partially or fully open (e.g., when book is opened on the platen for scanning and prevents the platen cover from closing completely). Therefore, there is a need in the art for a document scanner, an associated method of operating a document scanner and an associated program storage device wherein the scan mode and, more particularly, the light intensity level to scan rate setting, of the document scanner is automatically adjusted, as necessary, to fall within legal requirements and/or recommendations established to prevent vision damage and/or discomfort and still allow for high-resolution scanning.